Fans are complex rotating systems that may have undesirable characteristics caused by conditions encountered during normal operation. Fan flutter, for example, is a risk that fan designers and gas turbine engine designers consider. Fan flutter is an aeroelastic instability manifested as a vibrational response that is dependent on operating conditions such as frequency of rotation, fan blade characteristics, and flow path characteristics. Measuring fan flutter during design phases, for example, can be difficult. To study fan flutter, fan flutter should be generated in observable conditions. Fan flutter is elusive as it can be difficult to induce and measure. Thus, aero damping in systems experiencing fan flutter is difficult to design and measure.